Netflix defended its error messages to customers that blamed Verizon Communications’ network, despite a cease-and-desist notice from the broadband service provider.

In a reply to Verizon, Netflix’s General Counsel David Hyman wrote on Monday that the message cited by Verizon merely lets Netflix customers know that the Verizon network is crowded. Netflix said it had determined that by calculating the difference between the speed at which traffic was handled during peak and non-peak hours.

The video streaming company, however, said that the limited ‘transparency’ tests that had led to customers getting the error message would end June 16, though the company would evaluate rolling it out more broadly.

Regardless of the specific test, Netflix will continue to work on ways to communicate network conditions to its consumers, Hyman wrote, suggesting that the dispute between the two companies is far from settled.

Verizon threatened to sue Netflix last week after it started displaying error messages that blamed Verizon for low-quality video streams. Users received the message that the “The Verizon network is crowded right now” and that Netflix was adjusting the video for smoother playback.

The communications company asked Netflix in a letter to cease and desist from further providing the notices to its customers. It also asked Netflix to provide a list of its customers on the Verizon network to whom it has delivered the messages along with the date and time of display and the “purported substantiation” for the message.

In the cease-and-desist letter, Verizon’s General Counsel Randal S. Milch said that traffic on the Internet is affected by other factors including Netflix’s choices on how to connect to its consumers. It quoted a Internet Phenomena blog post to say that Netflix had tried to cut costs by using a “panoply of content-distribution and other middle-man networks” to reach customers.

Hyman countered that Verizon was trying to shift blame for its network problems, citing Verizon’s unwillingness to augment its access ports to major Internet backbone providers. He said it was Verizon’s responsibility to ensure its customers get the level of service they pay for, by ensuring that the network including the interconnection points have adequate capacity to meet customer’s data demands.

In its Netflix ISP Speed Index, a monthly update on ISP performance released Monday, the video company ranked Verizon’s average speed at the bottom at number 16 in the U.S.

“Some large US ISPs are erecting toll booths, providing sufficient capacity for services requested by their subscribers to flow through only when those services pay the toll,” according to a blog post Monday by company spokesman Joris Evers. ISPs must provide sufficient capacity in their network to provide consumers the broadband experience for which they pay, he added.

Netflix recently signed an agreement with Verizon that would bring its content directly on to Verizon’s network.

“We look forward to working with Netflix to improve our mutual customers’ enjoyment of Netflix,” Verizon said in an emailed statement. The company did not comment on whether it was now considering suing Netflix.

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